Gas-filled discharge tube circuits



Dec. 23, 1952 D. s. RIDLER ET AL 2,623,199

GAS-FILLED DISCHARGE TUBE CIRCUITS Filed Feb. 8, 1951 Inventors DEJMOND R/DLER DONALD A. wE/R Patented Dec. 23, 1952 GAS-FILLED DISCHARGE TUBE CIRCUITS Desmond Sydney Ridler and Donald Adams Weir, London, England, assignors to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application February 8, 1951, Serial No. 209,934 I In Great Britain February 17, 1950 6 Claims. (Cl. 315-169) v This invention relates to gas-filled multi-gap sequence discharge tube circuits.

In such tub circuits difliculty has been experienced in obtaining high speeds of operation. The object of the present invention is to overcome this difficulty.

The invention provides an electrical circuit comprising a gas-filled discharge tube having an array of anode/cathode gaps, means for applying pulses to said tube so that a single discharge is caused to travel in succession along said gaps and means for maintaining substantially constant the cathode potential of a discharging gap until the next gap in said array commences to conduct.

According to the invention there is also provided an electrical circuit comprising a gas-filled tube having a pair of discharge gaps, andmeans for applying pulses simultaneously to the circuits of said pair ofgaps in such a way that a discharge at the first gap is transferred to the'secnd of said pair and that the otential difference across said first gap is maintained substantially constant from the establishment of the discharge across said second gap to the cessation of the pulse application.

The invention further provides an electrical circuit comprising a gas-filled discharge tub having an array of main anode/cathode gaps and transfer gaps intermediate between adjacent pairs of main gaps, comprising a pulse supply, means for a plying pulses across the transfer gaps so that a single discharge is caused to travel in sucession along the main gaps and means for maintaining the potential difference across a main gap substantially constant during the puls application which eilects the firing of the next main gap in succession.

The invention will now be described by reference to on embodiment thereof shown in the accompanying drawings in which:

Fig. 1 shows part of a multi-gap gas discharge tube circuit which has been previously described;

Fig. 2 shows waveforms obtained at different points in the tube circuit of Fig. l as pulses are applied to the tube;

Fig. 3 is a diagram of a tube circuit according to an embodiment of the invention; and

Fig. 4 shows the waveforms for the Fig. 3 circuit.

In Fig. 1 there is shown part of a gas-filled multi-gap discharge tube in which there is an anode A, cathodes K1 and K3 and a transfer electrode K2. Each cathode is connected to ground over resistance-capacitance networks Ri/Ci.

Hz/C2 respectively. The transfer electrode K2 is commoned with other similar electrodes,' not shown, and connected to an inlet P to which nega tive-going pulses are applied. The anode A is connected to the positive high voltage supply over the anode resistance R3. Such tubes and their operation in such circuits have been previously described. The operation will be briefly outlined with reference to the Waveforms shown in Fig. 2.

Consider the tube initially with a discharge occurring across the A/K1 gap.

Counting pulse P1 is applied to the transfer cathode K2 causing the gap A/K2 to break down and consequently to increas the voltage drop across anode load resistance R3, which acts to reduce the voltage acrossgap A/K1 below the required maintenance valu thereby extinguishing said last named gap. Condenser C1 starts to discharge through R1. If the counting rate is high, say, 10 kc./s. with a pulse width of 25 microseconds and R1 and C1 have'such typical values as 12,000 ohms and .003 microfarad, then the potential on K1 will have decayed'to 50% of its original value on the trailing edge of the pulse and to 6% on the leading edge of the next pulse. When the pulse P1 disappears, the potential on K2 rises immediately, the discharge across A/Kz is extinguished and the discharge passes to the A/Ka gap due to the ionisation coupling of each gap with the other, and the potential of K3 there after rising as condenser C2 is charged up. However the potential of K3 only reaches of its maximum value. The effect of this short time constant resistance-capacity network required for high speeds is therefore (a) to increase the possibility of a retreat of the discharge from K2 to K1 due to the reduction in the charge on C1, which results in meagre tolerances.

(b) to reduce the available output voltage by about half, since the output is normally taken while the counting pulse is on. This disadvantage is indicated by the shaded portion of Fig. 2.

For these reasons operation at frequencies above 10 kc./s. has not proved to be entirely satisfactory.

In the new circuit arrangement incorporating this invention, the decay of potential of a cathode does not take place until the pulse is removed. This results in a large reduction of the time constant of the cathode resistance capacity network and use of the same tube is possible at much higher speeds.

Fig. 3 shows the improved circuit. Transformer T1 inverts the counting pulse and causes 3 rectifiers M1 and M2 to be blocked until the inverted pulse decays in transformer T1 so that no discharge of condenser C1 may take place during the pulse application and the full potential difference between K1 and K3 can be used for the output (see Fig. 4) the output being taken over terminals such as 01 and 02. Output arrangements may be provided for one or more cathodes. The previously conducting cathode, say K1, is, as before, held at an elevated potential during the pulse. This provides sufficient extinguishing time for the A/K1 gap. Thus the time constant circuit R1 C1 can be very short and have a minimum value which is determined by the time taken to establish the discharge on K3 after withdrawal of the pulse. It will be seen from Fig. 4 that P1 and P2 can bemovedmuch closer together before interference takes place between the rise and decay waveforms.

It should be noted that the output from T1 can be replaced by -a'-suitable positive-going pulse supply in-phas with the-pulses applied to the pointP, if this be more'convenient.

While the principles of the invention have been described above in connection with specific embodiments and particular modifications thereof, it is to be clearly understood that this description ismade only ,by-way of example and not as ailimitation on the scopeof the invention.

"What-we claim is:

1. An electricalcircuit comprising a as-filled discharge tube having electrode meansdefining a .pair of main gaps and a transfer gap intermediate said main gaps, a source'of pulses, means forapplying pulses from said source across said transfer gap, a separate storage circuit having a predetermined time constant associated .with each of said-main gaps to'store potential passed through saidgaps, means disposed between said source and said storage circuits and under control of pulses iifrom said source for delaying the discharge of the potential stored in said storage circuits, whereby the stored potential is maintained within said storage circuits independent of-the-time constants thereof, until the next "main "gapdn said arraycommences'to conduct.

2. An electrical circuit asclaimed in claim 1, wherein said delaying means comprises a pair of uni-directional devices, each serially connected between one of said storage circuits and 4 3. An electrical circuit as claimed in claim 1, wherein said discharge delaying means comprises a two-terminal rectifier element, means for developing pulses of identical phase but of opposite polarity of the pulses from said source,

saidelement'having one terminal coupled to said storage circuit and having another terminal coupled to said last-mentioned means, said rectifier element adapted to remain blocked during the 5. Anelectrical circuit comprising a gas-filled discharge tube having electrode means defining an array of main gaps and transfer gaps, each of said transfer gapsintermediate diiferent-pairs of said main gaps, a sourceof. pulses, means for applying pulses from said source across said transfer gaps so that a single discharge is caused to .travel in succession along said maingaps, a plurality of separate storage circuits, each having a predetermined time constant and each seriallyconnected with a different one of said main gaps and adapted to store potential passed through .said gaps, a plurality of two-terminal rectifier elements, each serially connected .between said pulse source .and a different one of saidstorage circuits and poled so as to remain blocked during the period of applicationof pulses to the gap with which each of said storage circuits and connected rectifier elements are associated.

,6. An ,-electrical :circuitas claimed in claim '3, wherein :said m eans ,for developing pulses :of

identical phase but of opposite polaritycomprises a tran former serially coupled between said source and said element, ,said transformer adapted to invert pulses received from said source.

DESMOND SYDNEY RIDLER. DONALD ADAMS REFERENCES CITED The following references are of record in the file of this patent:

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